METHOD FOR ALLOCATING INCOMING-CALL TO EXTENSION TELEPHONE SETS IN PRIVATE BRANCH EXCHANGE AND PRIVATE BRANCH EXCHANGE HAVING AUTOMATIC INCOMING-CALL ALLOCATING FUNCTION

摘要

In an integrated services digital network (ISDN),a caller number indicative of the telephone number of acaller can be usually attached in a call data. In aprivate branch exchange according to the presentinvention, the caller number of a caller and theextension number or numbers of an extension telephoneset or sets to which the call is desired to be directlysent from the caller are previously registered in asuitable memory table in a predetermined correlation,so that when the private branch exchange receives acall from the ISDN, it retrieves the table to checkwhether or not the received call is previouslyregistered in the table in the form of a caller number.When the call is registered one, the call ispreferentially allocated to one or ones of theextension telephone sets having one or ones of theextension numbers associated with the caller number ofthe received call. The number registration in thetable may be carried out through each of the extension-telephone sets.